Formation of lightining The ground and the electrosphere, the conductive zone of the atmosphere (thickness in the order of 50 to 100 km), constitute a natural spherical condenser which charges by ionization, leading to an electric field directed towards the ground in the order of a few hundreds of volts/meter. The building up of the stormy clouds, masses of water in the form of aerosols, comes with the electrostatic phenomena of charges separation: the light positively charged particles are pulled by the ascending airstreams, and the heavy negatively charged particles fall because of their weight. It also happens that small islands of positive charges are located at the base of the cloud, at the place of intense rains. All in all,